Remove redundant -DCMAKE_BUILD_TYPE=Release flags

Since commit 183d05a0 in 2012, this is the default.

fixes #18000

pkgs/games/openspades/default.nix

@@ -23,11 +23,14 @@ stdenv.mkDerivation rec {
     sed '1i#include <math.h>' -i Sources/Draw/SWFeatureLevel.h
   '';
 
-  nativeBuildInputs = 
+  nativeBuildInputs =
     [ cmake curl glew makeWrapper mesa SDL2 SDL2_image unzip wget zlib ]
     ++ lib.optional withOpenal openal;
 
-  cmakeFlags = [ "-DCMAKE_BUILD_TYPE=Release" "-DOPENSPADES_INSTALL_BINARY=bin" "-DOPENSPADES_RESOURCES=NO" ];
+  cmakeFlags = [
+    "-DOPENSPADES_INSTALL_BINARY=bin"
+    "-DOPENSPADES_RESOURCES=NO"
+  ];
 
   enableParallelBuilding = true;